Remote control system



June 19, 1951 E. TRIMAN REMOTE CONTROL SYSTEM 9 Sheets-Sheet 1 FiledFeb. 15, 1947 www June 19, 1951 E. L. TRIMAN REMOTE CONTROL SYSTEM 9Sheets-Sheet 2 Filed Feb. 15, 1947 June 19, 1951 E. L 'TRIMAN mom comm.SYSTEM 9 Sheets-Sheet 3 Filed Feb. 15, 1947 RNI E. L. TRIMAN REMOTECONTROL SYSTEM June 19, 1951 9 Sheets-Sheet 4 Filed Feb. l5, 1947 .m Tfn. I6

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June 19, 1951 E.L.1'R|MAN mom coNTRoL SYSTEM 9 SheeS-Sheet 9 Ill FiledFeb. 15, 1947 Patented June- 19, 1951 REMOTE ooN'rnoL SYSTEM Eugene L.Trlman, Chicago, Ill., assigner, by mesne assignments, to Bock-OlaManufacturing Corporation, Chicago, Ill., a corporation oi DelawareApplication February 15, 1947, Serial No. 'Ir-*28,765

17 claims. (ci. 177-353) This invention pertains to signalling andsignal controlled apparatus of general application, but particularlyuseful in conjunction with remote control systems and the like.

In its broader aspects, the invention has as one of its principalobjects the provision of means for transmitting a signal having acertain predetermined characteristic and utilizing the transmittedsignal to control a signal-matching means, at a receiving station, whichwill effect a matching or duplication of the characteristic of thetransmitted signal to provide a resultant control voltage or facto'ruseful in the' control of some desired instrumentality or apparatus.

More particularly, it is an object of the invention to provide a remotecontrol system utilizing a transmitted signal, for example a radiofrequency carrier modulated desirably as to frequency, phasing, pulseduration or sequence, modulation percentage, or the like, together witha signal-matching means operating under control of the transmittedsignal to provide a matching signal reproducing exactly the modulationcharacteristic of the transmitted signal, the identity or lack ofidentity of the matched and matching signals being utilized for controlpurposes, at a receiving station remote from the source of transmittedsignals.

Another objectof the invention is the provision of a remote controlsystem of general application, and especially useful in one of itsadaptations for the control of automatic phonographs and the like bysignals transmitted over a metallic circuit, including commercial powerlines, or by space wave propagation, the transmitted signal having acontrol characteristic and actuating a local signal generator at thereceiving station which is varied under control of the transmittedsignal until the locally generated signal is identical in controlcharacteristic to the transmitted signal, the identity or lack ofidentity between the transmitted and locally generated signals beingfactors in the actuation of the controlled device, in this instance, theautomatic phonograph, to effect for example the selection of'a certainphonographic record and the playing thereof.

A further objective aspect of the invention is the provision of remotecontrol apparatus for automatic phonographs and the like, which utilizesselecting signals transmitted Without a carrier over a metallic circuit,Vand in which selection is effected as a result of matching orduplication by a local signal generator of the transmitted signal toafford a resultant control voltage or factor.

2 Another particularized object is the provision of selecting meansactuated responsive to the matching or a 1oca1 signal with a transmittedselecting signal, both said signals being a phasal function oi astandard, alternating or pulsating voltage such as commonly suppliedover commercial power lines.

In accordance with one embodiment of the invention, a particular objectis the provision of selector-transmitter means including an oscillatoremitting radio frequency energy at measured or controlled intervals (forexample at standard power line frequencies), and selectively controlledmeans, for example push-button resistors, for determining the durationof the signal emission within the limits of said intervals,

as a function, for example, of phase shift in a voltage, derived fromsaid power lines, applied to the control grid circuit of saidoscillator.

Ancillary to the last-mentioned object is the provision of receivingselector means including a signal-matching pulse generator variable, forexample by motor means, to modify the duration of pulses generatedthereby, and a comparing circuit in whichthe incoming pulse ofpredetermined and selected length is compared with pulses from saidgenerator, and which controls the running of said motor until such timeas the generated signal is modiiied yto match the received signal, atwhich time said motor stops, the motor being utilized also to control adesired instrumentality.

In accordance with another object of the invention, there is providedselector-transmitting means emitting signals, for example at radiofrequency, which are modulated at a lower modulating frequency byphase-shifted control voltages the phase angle of which is selectiyelycontrolled, for example by push-button resistor means, the modulatingfrequency being desirably that of the power lines supplying the systemand/oi` carrying said signals, and thereby affording a standardreference frequency for modulation and phase shifting at bothtransmitting and receiving ends.

Incident to the last-mentioned object is the provision of selectivereceiving means cooperable with the selector-transmitting means thereof,which is characterized by the provision, among other features, ofphase-discriminating means upon which is impressed the incomingphasemodulated signal, as well as a locally generated signal or matchingvoltage the phase angle of which is progressively varied or modified, solong as signals are received, until the incoming and local signals areell'ectively matched and a predetermined or zero resultant controlvoltage is genauer produced in the discriminating means for desiredcontrol purposes.

A further object in conjunction with the selective receiving meanslast-mentioned, is the provision of phonograph record selecting controlmeans coacting with a step-by-step phase-shift selector switch whichmodifies the phase angle of the locally produced signal as aforesaid.

In accordance with still another embodiment of the invention, there isprovided a selectortransmitting means emitting a relatively continuouscarrier or radio frequency signal which is signal-modulated atselectively-*variable phase angle values, determined for example bypushbutton control or the like, or which, if desired, may befrequency-modulated selectively as a function of the aforesaidsignal-modulation angle in cases where disturbing amplitude modulationsare encountered on power lines transmitting the signals, for example.

Ancillary to the last-mentioned object, is the provision of selectivereceiving means in which the incoming signal is modified to a relativelynon-polar form and subjected to a shaping process to produce, forexample, signals the wave form of which is of a certain desired shape,and in which, further, there is produced locally a relativelynon-'polar'reference or matching signal of identical Awave shape, whichis subjected to a phase-shifting alteration or modiiication, undercontrol of incoming signals. until there is substantial identity inphase relation between the incoming and local signals to produce a localcontrol or selecting voltage.

Yet another object of the invention in its broader aspects, is theutilization of commercial power lines supplying, for example, a 60 cyclevoltage, as a transmission medium and/ or a source of modulating voltageand/or a frequency standard with reference to which controlling phaserelations in both transmitting and receiving apparatus may be comparedor derived.

In addition to the foregoing are other objects and aspects of noveltyand utility of detailed and complex character and pertaining tofunctional and circuit arrangements which are described and explained inview of the annexed drawings, in which:

Fig. 1 is a-block diagram of the remote control system in its broaderaspects;

Fig. 2 is a block diagram of a first embodiment of the system utilizingvariable pulse duration as the signalcharacteristic; l

Fig. 3 is a block diagram of a second embodiment of the system utilizingphase-shift modulation as the signal characteristic;

Fig. 4 is a block diagram of a signal-shaping receiver and generator ofparticular utility in conjunction with the system of Fig. 3;

Fig. 2-A is a circuit diagram for a selectoriransmitter for the variablepulse system of Fig.

Fig. 2-B is a circuit diagram for a receiving selector unit cooperablewith the transmitter of Fig. 2-A;

Fig. 3-A is a circuit diagram for a selectortransmitter for thephase-shift system depicted in Fig. 3;

Fig. 3-B is a circuit diagram for a receiving selector unit cooperablewith the phase-shift transmitter of Fig. 3-A;

Fig. 4.-A is a circuit diagram for a shapedwave phase-shift receivingselector cooperable, for example, with the transmitter of Fig. 3-A;

Fig. 5 is a circuit diagram of a modified Phaset shift transmitter andreceiving selector utilizing a metallic circuit without high-frequencycarrier.

Generalized description Broadly, the functional aspects of the novelremote control system are depicted in Fig. l, wherein a characteristiccontrol signal is emit- .ted from the block source I5 and transmitted byany medium to the remote point.

The characteristic of the control signal may be that of modulation as tofrequency, phasing, pulse duration, sequence, polarity, percentage ofmodulation, repetition rate of pulses, or combinathe matching signalgenerator of block i1, through the medium of a' control circuit meansI8.

If the incoming signal is characteristically modulated as to pulseduration, then it is the function of generating means Il to producesignals the duration of which is progressively varied above and belowsome limiting value, and these local signals are fed into a comparer I9,along with the actual incoming signals by-passed along path 20.

The vlocal generating means l1 will continue to produce signals ofdifferent pulse length until the generated signal is identical induration to the incoming control signal, at which time there is ineffect a zero resultant control voltage, preferably, which may beutilized in various ways to actuate the controlled device of block 22.

The aforesaid control voltage, as represented in block 2|, is somefunction of the incoming and locally generated signal voltages as theseare mutually effective in the comparer, it being apparent that theresultant control voltage may be zero or different from zero, forcontrol purposes.

Pulse duration system In Fig. 2 there are depicted diagrammatically thecomponents of a remote control system utilizing pulse duration as thecontrol characteristic. A forward pulse generator 25 produces pulseshaving a predetermined duration, as selectively varied for example bythe Master Control means there-indicated, and pulses of this durationare propagated or directed to the remote control point or receivingstation by transmitter means 26. In conjunction with the forward pulsegenerator, the master control is depicted schematically as aphase-shifting network, it being contemplated, as will more particularlyappear hereinafter, that the limiting values of the pulse duration mayconveniently be set between the beginning and end of a single cycle ofcommercial power line voltage, at 60 cycles for example, and theduration of such pulse may be controlled selectively by applying aneffective voltage at an instant during said cycle, determined by saidphase-shifting network, to the control grid of a thermionic pulsegenerator or an oscillator.

The transmitted pulse from the control station is suitably amplified bymeans 21 at the remote point, and rectied in signal detecting unit 28 Yto provide a positive incoming pulse for both control and comparisonpurposes; and this pulse is fed to a differentiating circuit means 29and also to a comparer circuit means 30.

The differentiating means, as will appear more particularly .in 4thecircuit description, functions to produce a short triggering pulse forcontrol of the local matching signal generator 32, which pulse isamplified in unit 3l. y

The local generating means 32 is preferably a single-cycle multivibratoradapted to produce in rapid succession, short pulses the duration ofwhich may be varied by varying a circuit component, such as the capacity'33, to produce what is preferably referred to as the reverse pulse,which is fed into the comparer circuit means 30. along with the positiveincoming pulse component from the detector stage 28.

If the incoming forward pulse and the locally generated reverse pulseare of substantially identical time duration, a thermionic controlcircuit or rectifier 34, actuated by the resultant control voltages fromthe comparer 30, will cause a master control motor 35 to stop. Thismotor is coupled to the reverse pulse generator control or capacity 33to vary the latter so long as the motor runs in one or the otherdirection, which it will continue to do so long as the forward andreverse pulses are not identical.' It will be apparent that the controlmotor 35 must always rotate predeterminedfa-mounts between opposite,fixed limits corresponding to positions of the capacity control 33 toeffect matching the local with incoming signals, by reason of which thismotor may also be utilized to control adesired device, such as aphonographiselector switch or the like.

In Fig. 2-A is shown a Wiring diagram for a selective control unit fortransmitting pulses of selectively varied duration in conjunction with aphonograph `control system, the transmission medium in this instancebeing the commercial power lines 40 supplying 60 cycle current to theprimary 4| of a power transformer, one secondary winding 42 of whichsupplies plate potential via lead 43 and R. F. choke 44 tothe plate 45of a thermionic oscillator tube, the plate circuit being completed tothe cathode 46 mainly via leads 41, coin switch 48, closed momentarilyby deposit of a coin in the usual coin control (not shown) provided forphonograph selectors, and conductor 49 back to said high-potentialsecondary winding 42 through the Winding 50 of-a locking relay andconductor 5I.

The momentary flow of plate current in the aforesaid plate circuit willcause the locking relay to pull up and close its own interlock circuitvia4 contacts 52, normally closed contacts 53-54 and cathode lead 41, atiming capacity 55 being shunted across relay winding 50 through relaycontacts 55, so that the relay continues to hold up although platecurrent is flowing only during half-wave intervals of the 60 cyclesupply voltage.

The grid circuit of the oscillator tube, from grid 58 connects throughgrid condenser and leak 59 to one terminal 60 of a vtank inductance, theopposite terminal 6| of which is coupled through capacity 62 to plate45, and via conductor 63 and line coupling capacity 64 to one side ofthe power lines 40. This grid circuit is completed to cathode from tap66 on the tank coil via conductor 61 and radio frequency capacitor 68 tocathode 4B, the tank coil being tuned to the desired line transmissionfrequency by shunt capacitor 59.

Normally, contacts 10, ganged with contact 54.

are closed to complete a short circuit' around grid inductance Gil-66via conductors 61A and 1l, as a result of which the oscillation of theaforesaid oircuit is prevented until such time as one of the selectorpush buttons 12A, 12B 12G is depressed for* purposes of effecting aphonographic selection.

When the locking relay has its coil 50 energized 'as aforesaid,following deposit of a coin. a mechanical interlock (indicatedschematically by l the dash-dot line, switches 54, 10) is set up bywhich any of the push buttons 12A 12G depressed will be locked in set orclosed condition; and as one result of the selective depression andlocking-in of. say, the push button 12B, switch contact 54 will betransferred from contact 53 to contact 53A, and also, contacts 10 willbe opened, lifting the short-circuit around grid inductance Ell-66, sothat the oscillator circuit may now oscillate during appropriatehalf-wave intervals of the supply frequency.

As another important incident of setting of selector push button 12B asaforesaid, contacts 13B thereof close, thereby connecting the tank coilcathode lead 61 through a phase-shifting resistor 14B, conductor 15 toone terminal of a phase-shift grid-bias secondary winding 16 of theaforesaid power transformer, the remaining terminal of which windingconnects via conductor 11 and series phase-shift capacity 18, conductor1S, and phase-shift resistors 14H, 14G 14C to the depressed push buttoncontacts 13B, by reason of which a grid-biasing voltage is applied toconductor 61A from winding 16,*the phase of which is shifted (in apredetermined amount dependent upon the values of phase-shiftingcomponents 18 and the connection to the resistor network 14B 14H;relative to the plate Voltage.

As a result of applying a selectively phased grid bias to the oscillatorduring intervals of oscillation as aforesaid, radio frequency impulsesof selected duration are impressed upon the power lines 40 throughcoupling means or capacities 64, E5, to be picked up by remotelysituated receiving and selecting apparatus now to be described.

A plurality of selecting pulses of predetermined duration will beimpressed upon the transmission medium or power lines followingdepression of one of the selection push buttons as aforesaid, thesepulses following in very rapid succession for a determined length oftime considered adequate to assure response at the remote controlledstation, said length of time being dependent upon thetime required forthe timing capacity 55 to discharge, it being recalled that as anincident to depression of a push button, contact 54 transferred tocontact 53A, thereby shunting the cathode return 41 around relay winding50 Via contacts 53B and lead 53C to conductor 5|. As soon as the relayfalls back, both the electrical and mechanical interlocks set up therebyare broken, with the result that contacts 10,'controlling oscillation,and contact 54, are restored. to normal condition, awaiting the nextcoin-operation of the control unit, and the particular push button whichhad been depressed and locked down, is freed and normalized.

In Figure 2-B is shown a circuit diagram of a pulse-duration selectingmeans, wherein the pulse generating and transmitting means indicateddiagrammatically in blocks and 8l apply a selecting pulse at radiofrequency, for example,

to power -lines 40, from which the pulse signals are picked up bysuitable coupling means, e. g. the line coupling capacities indicated,and passed through a suitable amplifying means 82, preferably, beforerectification by the usual signal detecting means 83.

The rectified incoming selecting pulses are fed to a differentiatingmeans through coupling transformer 84, said means consisting in thisinstance of capacity 85 and resistance 85 calculated to give a timeconstant resulting in a very short pulse for triggering the local pulsegenerating means, this triggering pulse being coupled via conductors 81to the grid-cathode circuit, including bias potential means 80, ofbiased amplifier means 89.

The differential triggering pulse, after ampliiication by the biasedamplifying means 89, is applied via conductor 90 to the grid 9|, of oneof a pair of triodes in the local signal generator, through couplingcapacity 92, cathode 93 for this triode being returned to the commonground 94.

The local signal-matching generating means is depicted as a form ofsingle cycle multivibrator in which pulse changes in the circuit 95 ofrst triode plate 98 are coupled through a variable capacity 91 to thecontrol grid 98 of a second triode, which is coupled through parallelcapacity 99 and resistance |00-to the generator output lead |0I, alongwith the grid 9| of the iirst triode. Capacity 91 controls the durationof each pulse generated by this signal-matching means, responsive totriggering impulses from the diiferentiator, and said capacity isarranged to be progressively, and in a sense retrogressively, varied bymeans such as the motor |05, which, as will appear, is connected to runin opposite directions so long as the incoming and locally generatedsignals do not match in duration.

Means for comparing the locally generated matching signal and theincoming control signal includes a comparer consisting of a first gastriode or Thyratron V1, the control grid |08 of which is coupled throughcapacity |01, conductor |08, to the line side of diiferentiator capacity85, so that the same signal utilized for triggering is impressed uponthe grid of the iirst gas triode to fire the latter, while the localmatching signal is applied from generator output lead through capacity|09 to the control grid ||0 of a second gas triode V2 in the comparer tolire the same. The plates of both triodes V1 and V2 are supplied from aquenching supply voltage source of suitably high frequency, for exampleabout 420 cycles, adequate to provide rapid restoration of the twocomparer triodes in comparison with the pulse frequency. The plates I4and I I5 of gas triodes V1 and V2, respectively, are connected toterminals |I6 and |I1 of an anode supply transformer whose primary |I8is connected to the aforesaid quenching supply frequency sourcesecondary connection ||1 being a center tap which connects throughbridge resistor means |I`9 to said plate I I and also to the cathode |20of triode V1, said resistor being grounded as at |2I, and each bridgeresistance section being shunted by capacity |22, while the thirdterminal of said transformer connects to the cathode |23 of triode V2.The outer terminals of the bridge resistor arms connect respectively viaconductors |24 and |25 to control grids |26 and |21 of a second pair ofgas triodes T1 and T2 constituting the Master Motor Control unit,so-designated, Fig. 2-B, said grids being connected together through thearms of bride resistor means |29. A biasing voltage supply |30 isconnected, positive, to cathodes |3| and |32 of the second pair oftriodes. and negative to the common connection of the arms of the secondbridge resistor means |29 and to ground at |33.

The anode supply voltage for the plates o! the second set of gas triodesis procured from the secondary windings |36 and |31 of a transformerwhose primary |38 issupplied from the 60 cycle mains, said windings |36and |31 having a common center tap connection |39 to ground and beingrespectively connected through motor eld windings |36A and I31A toplates |34 and |35; thus, plate current flowing in either triode T1 orT2 will excite the corresponding eld winding of the Reversible MasterMotor |05.

By reason of the normal biasing voltage from source |30, both of thesecond Master Control triodes T1 and T2 are normally quenched, so thatthe motor fields are not excited and the motor |05 is at rest; however,an effective positive grid voltage in either arm of the bridge resistormeans IIS, |29, |2|, |33, will re the corresponding triode, with aresultant excitation of the corresponding field winding |36A or |31A andconsequent armature rotation in a certain direction depending upon thepoling of the amature supply voltage |40.

An incoming control signal impressed upon the grid of comparer triode V1would cause control triode T1 to fire, and the consequent plate currentflow through motor winding |31A would start the master motor in a firstdirection, with a consequent progressive change in the capacity ofvariable control means or condenser 91 of the local generator.

The same incoming control signal would trigger said local generator andthe pulse generated thereby would be impressed upon the control grid ofthe second comparer tube Vz in phase with the signal voltage applied totube V1, so that under the incoming and locally generated pulses, thecomparer triodes are iired and restored sio multaneously in very rapidsuccession if the said pulsos are identical in length, under whichcondition, the resultant voltage in the bridge circuit ||9, |2I, |29,|33, is effectively zero, in consequence of which neither control triodeT1 or Tz would fire, and motor |05 would be at rest.

However, so long as the incoming and locally generated pulses are ofdiierent duration, the aforesaid bridge circuit will be in eiectunbalanced with a resultant control voltage that will fire one or theother control triode T1 or T2. and the master motor will run untilvariable control means 91 tunes the local pulse generating means toproduce the identical pulse necessary to match the incoming pulse 'for azero resultant control voltage in the bridge circuit. In thisconnection, it is important to notice that the direction of rotation ofmotor |05 is correlated to the operation of generator capacity 91 andthe relative iiring relationship of tubes V1-T1 and Va-Tz such that therelative displacement of capacity 91 will tend to shorten the durationof the local pulse if the latter is too long, and vice versa.

The pulse-duration embodiment of the invention hereinabove described inView of Figs. 2, 2A, 2B, may be utilized to control any desired deviceor instrumentality, preferably by interconnecting such device with thedriving link, indicated by the dash-dot line |42, Fig. 2B, whichconnects motor |05 with pulse duration control means 91,

ldevice |43 and link line |44.

Phase-shift selective system Depicted in Fig. 3 by block diagram arecomponents of an embodiment of the invention utilizing phase-shiftedselecting signals, preferably modulating radio frequency carrier currentapplied to the commercial 60 cycle power lines for controllinginstrumentalities at the remote station.

To this end, a source of radio frequency carrier current |50 at theremote selecting station is applied to the transmission medium, here thepower lines |5|, at a frequency for example of 185 kc., this energybeing modulated by selecting signals from a selective phase-shiftingsignal control means |52, for which the phase-shift reference standardis the 60 cycle line voltage as indicated at |54.

At the controlled or receiving station, a resonant filter means |55 ispreferably included ahead of an input signal amplifier, |56, both thefilter and amplifier being tuned or peaked critically at the carrierfrequency of 185 kc. to eliminate or suppress transients and spurioussignals, and the incoming carrier is rectified or detected by the means|51 for derivation of the positive signal pulses which are thenimpressed upon a 60 cycle phase discriminating means |58, as well asupon a 60 cycle rectifying means |59 which controlscertain control relaymeans |60 and |6| functioning ultimately to energize or close the localselector circuit indicated at |62 cooperatively with a localThyratron-controlled rotary switch means |63 actuating a local 60 cyclephaseshift network means |64 (operating preferably step-by-step throughinterrupter switch means |65 cooperative with the Thyratron switchmeans).

By way of general description of operation of the system shown in Fig.3, it may be assumed that the 60 cycle power lines |54, |54', and |54are part of the same commercial feeding line, which therefore in thiscase is both the transmission agency or medium and the phase-shiftreference standard.

Assuming that a certain selection is made at the controlling station bymeans of the signal control |52, Fig. 3, an R. F. frequency will beimpressed upon the power lines aforesaid by the 185 kc. oscillator means|50, and this R. F. carrier is modulated by the 60 cycle selectingfrequency in which the phase of the modulating voltage depends upon theselection made by control |52.

The aforesaid 185 kc. carrier, thus modulated, is passed from the powerlines by filter |55 and amplified by means |56, and the positive half(preferably) of the amplified signal is detected by means |51 forderivation of a selecting signal voltage, which in turn is passed intothe discriminator |58 and also to rectifying means |59.

So long as there is a signal voltage component acting in thediscriminator output circuit, the Thyratron controlled switch |63 willcontinue to step cooperatively with interrupter switch means |65, with aconsequent progressive shifting of phase constants in the network means|64, there being an a. c. line voltage fed into the phase-shiftingnetwork from line source |54', and this line voltage, modified as tophase, is equivalent to a locally generated signal, which is fed intothe discriminator for comparison with the phase characteristic of theincoming selecting or control signal.

At such time as the local phase-shifted signal and the incoming phasallycharacteristic signal are or become identical. there will be noresultant voltage component in the discriminator output network-in otherwords, there will be a null. by reason of which the stepping switchmeans |63 stops and the control relay means |60, |6|, complete theircontrol functions to cause a closure or energization of the selectorcircuit |62.

Referring to Fig. 3-A, showing a transmission-selector controlunit ofthe phase-shift type suitable for use in conjunction with the system ofFig. 3, there are provided a plurality of selecting push buttons |19,usually twelve to twentyfour in number for adaptation of the system tocontrol of an automatic, coin-operated phonograph, and these pushbuttons are preferably of a known type adapted to lock, when depressed,and to be released from locked or selecting position by shifting ofmeans such as the lock bar 1|.

Each said push button is operatively linked with phase-shifting meanssuch as the variable resistance |12 in series with phase-shiftingcapacity means |13 and secondary winding |14 of a transformer whoseprimary |15 is connected to commercial power line leads |16 and |11,over which the control or selecting signals will be transmitted to aremote receiving selector means or station |80.

A locking relay |8| is connected to line |16 through rectifying means|98 and R. F. choke means |99. The other side of the locking relay |8|is connectable to line |11 through a coin operated or controlled switch|18 closable from normally open condition to complete the circuit vialead |11A to the main power line conductors |11. When the coin switch|18 is closed, the locking relay |8| is energized long enough to lockitself mechanically and close itscontacts |82 and |83, the latterclosing an operating circuit for latch bar solenoid |84, therebyreleasing the push button latch bar means |1| to restorev any and allpush buttons to normal or non-selecting positions.

Following coin operation of switch |18 and release of all push buttons|10 as aforesaid, a selection may be made by depressing one of said pushbuttons, which becomes locked by lock bar means |1| with a consequentclosure of contacts |85, which, together with now locked contact |82,shunts out the cathode resistor |86 of a gas triode or Thyratron |81,and thereby affording a lowresistance cathode return, via said contacts|86, |82, to connection |88 with conductor |11, and via lead |89 from anR. F. amplifier cathode |90. thereby causing radio frequency energy at185 k. c. to be placed on the transmission line conductors |16 and |11,as will presently appear.

As a further result of closure of contacts |82, |85, a timing circuit,including condenser |9| and resistance |92 is rendered effective inthat'the condenser |9| is permitted to discharge slowly through saidresistance, lthereby impressing a high negative bias on the grid |93 ofthe Thyratron |81, preventing the latter from firing.

The 185 k. c. carrier frequency is supplied by oscillator tube |94,whose plate |95 is energized through resistors |96, |91, and rectifyingmeans |98, through radio frequency choke means |99, and power line lead|16, cathode 206, as well as cathode 20| of the companion modulatortube, being connected through resistor 202, lead 203 to the other linelead |11, while the plate of the modulator tube, 204 is fed throughdropping resistor 205 from the supply to plate |95.

The control grid 206 of the modulator tube has impressed thereon'aselective o'r characteristic phase-shift voltage from the network means|12, |13 and line voltage source |14, which may be a winding on thefilament transformer supplying the tubes of this unit, the primarywinding |14A of which is energized from line leads |16 and |11, therebeing a vreturn lead |14B from center tap on secondary winding |14 tolead |11 for the modulating voltage.

' Tuning of the carrier energy to the desired frequency, e. g. 185 k.c.. is effected by a tank circuit including inductance 2|0 and capacity2|| connected to grid 2 |2 of an R. F. amplifying tube via conductor2|3, which grid is returned to ground via conductor |89 and contacts|82, |85, closed. Amplifier grid 2 I2 is also looped via lead 2 |4 withthe control grid 2|5 of the oscillator tube, the latter grid beingcoupled through capacity 2|6 to plate 204 of the phase-shifter modulatortube, it being understood in this connection that the carrier here isamplitude-modulated, and the signal is phasally modulated or varied.

The system in this form can also be frequency modulated if desired, inwhich case the tank circuit combination 2|02|| is substituted forcapacity 2|6 and a return resistance substituted for the tank betweenconductors |89 and 2|3.

The amplified, phased-modulation (to distinguish from the ordinaryphase-modulation of a carrier as a form of frequency modulation) carrerenergy is transferred to the transmission line through R. F. transformer2|1, the primary of which is in the power circuit for plate 2|8 of theamplifier, and the secondary of which connects via conductor 2|9 withpower line lead |11, and via coupling capacity 220 with power line lead|16, from which the phased-modulation carrier is passed onto the mainpower lines |19, along with similar signal energy from other selectorcontrol units 22|, etc. connected with the same power lines toselectively control the operation of automatic phonograph means 222,through agency of the receiving selector means indicated schematicallyat |80, Fig.3-A, the function of which is to produce a local signalvarying progressively between certain limits in phasal characteristicuntil the phasal characteristic of the incoming control or selectingsignal is matched exactly to cause selection of the desired phonographicnumber corresponding to the particular phasal identity of the localmatching signal.

When the selector switch or button lock release is actuated responsiveto energization of coil |84 as aforesaid, following initialcoin-operation of the lock relay |8|, the latter remains locked, but theoperation of the latter in closing release contacts |83 is onlymomentary, and nothing happens until one of the selecting buttons ispushed, to become mechanically locked in operated condition again andalso to close contacts |85, thereby completing the aforesaid shuntaround cathode resistor |86.

After a predetermined time, timing capacity |9| will have dischargedsuiciently through contacts |85, closed, to reduce the negative bias onthe tube |93 to permit the latter to nre, thereby again momentarilyclosing release contacts |83 so that the latch bar |1| is again trippedto release the selected button, and accordingly, contacts |95 areopened, restoring resistor |86 and interrupting the emission of thesignal. For this purpose, relay |8| is an impulse type, locking relaywhich only momentarily closes contacts |83, but will hold contacts |82lockedclosed.

'I'he receiving selector means depicted by block diagram at |80 in Fig.3A isv shown in detail in Fig. 3-B, wherein the' selecting or controlsignals incoming from one or another of the remote control stations, arepicked up from the power line leads |19 through coupling capacities 225,amplified by R. F. amplifier means 228, and passed through couplingtransformer 221 to plate 228 and cathode 229 of a demodulator ordetector to reproduce the original phasally modulated signal separatefrom the carrier, the secondary of input transformer 221 being tuned bycapacity 230 to the carrier frequency, and completing the rectifyingplate circuit through dropping resistor 23|, suitably by-passed at 232,through the primary 233 of a coupling transformer, to the cathode 229.

The demodulated signal voltage appearing across the secondary winding234 is impressed upon plates 235 and 236 of a pair of diodes formingpart of a 60-cyc1e phase discriminator, the cathodes 235A and 236A ofwhich respectively connect to the control grids 231 and 238 of a pair ofgas triodes or Thyratrons or relay tubes, said grids being negativelybiased by battery or source 239 connected between cathode lead 240 andthe center tap of resistance 239A.

Cathode lead 240 is connected to stepping switch interrupter terminal24|, normally in closed circuit condition with stepping switchinterrupter contact 242, grounded at 243, and also connected through thestepping switch coil 245 to the negative terminal of the plate supply orbattery 244 for the Thyratrons.

The demodulated signal energy applied to discriminator plates 235 and236 appears as a positive D. C. voltage across the load resistors 235Band 236B in opposition to the negative biasing voltage of battery 239 toswing the control grids 231 and 238 of the Thyratrons positive and firethe relay tubes so long as there continues to be sufiicient voltageacross said load resistors, which is the case until the local matchingsignal generator operates selectively to nullify said firing voltage.Each time the gas triodes or Thyratrons re as aforesaid, the steppingswitch coil 245 is energized to actuate the interrupter switch contact242, as well as the phase-shift selector wiper 250 and the recordselector switch wiper 260, it being apparent that each opening ofcontact 242 from the normal contact 24| interrupts the cathodeplatecircuit of the Thyratrons and quenches the latter, and since theselecting signals come in rapid succession, the tubes are rapidly firedand restored, and stepping switch coil 245 is rapidly pulsed to step thewipers around their respective banks of contacts.

Assuming that twelve selecting positions are required, corresponding forexample to twelve phonograph record selections, wiper 250 will traversetwelve contacts 25|, each connecting with one terminal of aphase-shifting means, such as resistors 252, the remaining terminals ofwhich are all commoned to conductor 253 leading to one terminal of a60-cycle voltage source, which in this instance is the secondary of atransformer, indicated at 254, the primary 255 of which is connected tothe power mains |19.

The remaining transformer secondary terminal 256 connects to anotherphase-shift component or means such as the capacity 251, connecting vialead 258 to center tap 234A on the secondary of the discriminator inputtransformer.' and voltage source secondary winding 254 has center tap254A connected via conductor 259 to the mid-tap 235C of thediscriminator load resistors, as a result of which a local .signalhaving a phase angle selectively determined by the position of wiper 250on the bank of resistor contacts 25|, is applied to the phasediscriminator circuit at points 234A and 235C.

In the example disclosed, only twelve selecting intervals are required;however, a much larger number may be had. In general, the values for theseveral resistors 252, with regard to their calculated effect, inconjunction with capacity 251, on the phase angle, are chosen to aord amaximum interval separation between each step in the bank. Thus, aswiper 250 steps over contact bank 25| responsive to signal-initiatedring and quenching of the gas triodes, it will lodge on a contact 25|the corresponding resistance 252 for which, in cooperation with capacity251, will result in the application of a local vsignal voltagesubstantially identical in phase angle to the incoming, demodulated,signal voltage, by reason of which any triggering or ring voltageexisting'in the Thyratron or relay tube inputs circuit is nulled, andthe stepping switch remains at rest with phase-shift wiper 250 on aparticular contact in the bank, and with phonograph selector wiper 260on a correlated and particular contact in its bank 26|, awaiting theiinal selecting operation determined by certain control relay means nowto be described.

A first control relay having one terminal 210 f its winding connectedcontrol tube or rectifier, has its remaining terminal 212 connected viaconductor 213 and normally closed contacts 214 of a second controlrelay, in series via-lead 215 with plate supply source or battery 216 tocathode 211, such that plate current owing in said control tube willcause said first control relay to pull up. However, the control grid 218of said control tube connects through resistor 219 to the negativeterminal of bias battery or source 280, which normally suppresses platecurrent flow in said tube, so that the control relays are idle andnormal while incoming selecting signals are received, until the localgenerator matches signals.

Control grid 218 connects via conductor 28| I and resistor 282 todemodulator resistor 23|, deriving from the latter a positive voltagecomponent of the diode current, which is thus applied to the controlgrid of the control or rectifier tube with the object of chargingcondenser 283, shunted between grid 218 and the negative bias terminal,and grounded at 284.

However, the charging effect of each positive diode voltage pulse isnullified by operations of the interrupter switch and closures ofcontact 242 with contact 286, thus applying ground from 243, viaconductor 285, to the normally ungrounded termin of condenser 283, sothat the latter is prevente' from charging up to potential suillcient toeiect substantial plate current flow in the circuit of plate 21|.

When the selective operation of the phaseshifting means is completed bysignal-matching as aforesaid, interrupter switch 242 remains at rest,normal on contact 24|, and condenser 283 has an opportunity to charge upunder continued positive pulsing from the incoming signal energy in thedemodulator circuit, and very quickly reaches a potential suflicient toovercome bias 280 to the plate 21| of awith a resultant ilow of platecurrent through the winding of the rst control relay at 210, 212, as aresult of which contacts 290 close, applying battery from plate supply216, via conductors 28|, 292 to terminal 293 of the second control relaycoil, the remaining terminal 294 of which also connects with plate 21|,so that the second relay pulls up, ting the first control relay out ofthe plate circuit, while simultaneously closing contacts 295 to lockin aholding circuit from second relay coil terminal 293, via conductors 298,29| to plate supply source 216.

As a result of the initial pulling up of said ilrst control relay, itscontacts 291 were closed, thereby completing circuit via conductors 298,between battery or power source 299, wiper 260, and the particularselector coil 300 contacted by said wiper, thereby causing the means 30|to play the selected number. `Another result of initial energization ofsaid rst control relay is the closure of lock-out contacts 302, whichplaces a shunt, via conductors 303, across the grid input circuit forthe Thyratrons, thereby shorting out all impulses from the discriminatorso that the relay tubes cannot possibly re for the remaining duration ofthe incoming selecting signals, once a selection has been made.

As soon as said first control relay drops back, upon operation of thesecond control relay, as aforesaid! rst lock-out contacts 302 open, butnot Abefore a second lock-out pair 304 closes, placing the same lockoutshunt via conductors 303 on the grids of the Thyratrons.

As soon as the incoming selecting signals cease, condenser 283 bleedsoff quickly through resistor 219, andl plate current is again suppressedby bias 280, so that the second and locked-in control relay falls back,and ness for the next selecting operation.

Direct-comparison phase-shift system In Fig. 4 is shown by block diagrama modification of the selective means of Fig. 3B, which is likewiseadapted for cooperation with the transmitter-selector control unit shownin Fig. 3A.

Incoming signals, preferably filtered and amplied, as by means |55, |56,Fig. 3, are detected or rectified for demodulation purposes by meansindicated in block 400, which may correspond to block |51 of Fig. 3, andthe signal is then passed to a depolarizing bridge 40|, which in effectdoubles the signal frequency and aiords a unidirectional signal voltageof desired polarity without regard to poling of the power lineconnection.

From the depolarizing bridge, the incoming selecting signals are shapedas to wave form by signal-shaping means 432 to provide substantiallysquare-Wave pulses of optimum matching form.

Means locally generating matching signals includes a source ofalternating voltage of the same frequency as the modulating source,derived in this instance from the power lines |19 via transformer 404,the secondary voltage of which is phasally modied by phase-shiftingmeans generally indicated at 405, and which voltage is passed throughdepolarizing means 406, such that uni-directional pulses of linefrequency and desired polarity are produced for square-wave shaping bymeans 401.

'I'he shaped incoming and local pulses from means 402 and 401 are bothapplied to selecting opening contacts 214 and thereby cutautomaticphonograph the selecting means is in readithe input of the relay controltube, the plate assumer y relay means 408, in accordance with the directcomparison method hereinafter explained, such relay means being forexample a Thyratron valve, and the pulses being in opposition, such thatif they are also in phase, the relay means 409 is not actuated,whereupon the control relay means 463, by 4|9, pulses 409 for selectedoperation of the controlled device, such as phonograph 222, Fig. 3--A,or 30|, Fig. 3B. Should the two signals not match in phase, however,then the phaseshifting means would continue to operate until they didmatch, following which, selection would be made.

Referring to the circuit diagram of Fig. 4-A, the incoming phase-shiftselecting signals from line |19 are amplified by means 4|5 anddemodulated by means 4|6, which may be the usual rectifying means or adiscriminating network, depending upon whether the incoming carrierenergy is amplitude or frequency modulated.

The demodulated incoming signal energy 1s applied to a depolarizingrectifier network or bridge 4|1, one output terminal 4|8 of which 1sconnected to control grid 420 of signal shaperamplifier 42|, the otheroutput terminal 4|9 of said bridge being connected to the common ground422, along with cathode 423. The incoming signal energy is furthershaped and amplified by tube 424, whose control grid 425 is coupled bycapacity 426 to plate 421 of the preceding stage; plates 421 and 428 areconnected through dropping resistors 429 to the common platee supplylead 430.

Shaper plate 428 is coupled by capacity 43| to the controlgrid 432 ofthe last shaping tube 433, and also through series capacity 43|A to thecontrol grid 434 of a relay control tube 435, the incoming signals beingamplified as well as shaped to square-wave form, as aforesaid, andappliedhl of which connects via conductor 431 to one terminal 348 ofcontrol relay winding 439, in series through terminals 440 with a secondcontrol relay winding 44| the remaining terminal 442 of which connectsvia lead 430A to the common plate supply conductor 430.

Amplifier-shaped catliodes 423, 424A, and 433A are returned to commonground 422, cathode 433A being connected to ground at 5|1 through theIlock-out normal contacts 5|6X of phonograph control relay 439; but therelay control tube cathode 435A is grounded through a variable resistor443 for sensitivity adjustment of this stage in actuating (and droppingout) the control relays in the plate circuit thereof, such that relaywindings 439 and 44| will be adequately and not marginally energized byplate current iiow to cause said relays to pull up positively and atonce upon matching of selecting signals. All control grids are returnedto ground through resistors 445.

The plate 446 of the Shaper tube 433 connects through resistor 441, lead448, to plate 449 of the local matching Shaper tube 450, which plate inturn connects through dropping resistor 45| to the positive plate supplylead 430A, it being pointed out at this juncture, that the outputs ofboth signal or pulse shaping circuits are therefore directly broughttogether at junction 452, and in this sense are directly compared, asdistinguished, for example, from comparison in a network ordiscriminator means of the 'type employed in the circuit of Fig. 3B.

Locally generated matching pulses are derived from a frequency standardsource, such as the power mains |19, over which the incomingselecting-signal energy or carrier may be assumed to be transmitted,transformer 460 having its prirnary 46| connected to saidr mains, andits secondary 462 shunted by center-tapped resistor 463, with oneterminal of said resistor connecting to capacity 464 as one element of aphaseshifting means, and the remaining terminal of said resistorconnecting in common at bus jumper 465 with one terminal of each of aplurality of phase-shift resistors 466, the number of which is the sameas the number of selecting positions or operations the device isintended to make, for example, twelve in the case of a twelve-recordphonograph selector mechanism. The remaining terminal of each of saidphase-shift resistors connects with a contact 461 in a switch bank, tobe engaged step-by-step by switch wiper contact 468, which is connectedat 469 to capacity 464, and at 410 to one input terminal of the localdepolarizing bridge.

Center tap 41| of shunt resistor 463 connects via conductor 412 to theremaining input terminal 413 of said bridge. Thus, a local matchingvoltage is applied to the depolarizing bridge, and

.the phase angle of this voltage is determined selectively by theposition of the Wiper 468 on the bank of phase-shift resistor contacts461, such that a particular value of resistance is in series withcapacity 464 as a phase-shifting network across the transformersecondary 462 depending upon the position to which said wiper has beenstepped by operation of stepping switch means shortly to be described.

One output terminal 415 of the depolarizing bridge connects to commonground at 416, while the remaining terminal of the output connects viaconductor 411 to control grid 418 of Shaperamplifier 419, the plate 480of which connects through resistor 48| to positive plate supply branch430A and is coupled through capacity 482 to control grid 483 of thelocal or reference shaper tube 450, so that the local pulses, at doubleline frequency, are squared conformably to the shaping of the incomingpulses at like frequency, said pulses being present at juncture 452simultaneously, in a manner of speaking, but in opposing sign, such thatif the respective pulse voltages are in phase, there will be a minimumresultant voltage at the comparing juncture 452, but if the pulses arenot of identical phase angle, or substantially so, the resultant voltageat said juncture will be sufficient to actuate the selecting relaymeans, which in this case is a gas tetrode or Thyratron 490.

The aforesaid selecting relay means or Thyratron 490 includes in itsplate circuit the winding 49| of 'a stepping switch mechanism, whichactuates the phase-shift wiper contact 468 in step with a similar switchwiper 492 for the phonograph (or other) selector switch. One terminal493 of said winding connects with the positive plate supply lead 430,and the remaining terminal of this coil, 494, connects normally throughstep switch contacts 495, 496, conductor 491, with plate 498; thus, eachtime the selecting relay Thyratron fires, step switch coil 49| isenergized to actuate the associated stepping mechanism (not shown) andcause wipers 468 and 492 to advance one step or contact in unison, andto cause step switch contacts 495-496 to open, thus opening the platecircuit for the Thyratron and quenching the same, plate lead contact 496at this time closing with contact 499 shorting plate 498 directly tocathode 500 around a cie-ionization capacity 50| to hasten the completerestoration and quenching of the Thyratron, in view of the rapidity ofthe selecting pulsations, and the corresponding normalization of thestepping switch mechanism and contact system.

For increased sensitivity and simplification of equipment by eliminationof amplifying means otherwise necessary, the relay tube 490 is a tetrodehaving a shield grid 502 tied to the cathode 500, said latter elementsconnecting through resistor 503 to terminal 493 on the hot side or platevoltage supply side of relay winding 49 I, said resistor 503 beingcalculated to permit a slight cathode current so that' there will beadequate biasing voltage drop to bias the control grid 504 negatively.

Application of the resultant comparison voltages present at junction 452of the two pulsesquaring Shaper circuits, is effected through capacity505, which connects by conductor 506 to the cathode 500 of the gastetrode relay tube to apply a negative voltage thereto adequate to swingthe control grid positive and re the tube.

The reference or standardmatching pulse generating means is poled sothat its pulse voltages, alone in the absence of incoming selectingpulses, will not be of polarity to lire the relay tube.

So long as the incoming and locally generated pulses are notsubstantially identical in phase, there will be a resultant voltageadequate to re the Thyratron 490 repeatedly for the duration of incomingsignals, with a consequent repeated stepping of wipers 468 and 492; andas the former lodges in succession upon diilerent contacts 461,different values of phase-shifting circuit component or, in thisinstance, resistance, will be connected in circuit with component orcapacity 464, and this operation will continue until the phase angles ofthe local and incoming pulses are substantially identical, at which timethere will be no resultant effective voltage adequate to re theselecting relay or Thyratron 490, with the result that the steppingswitch will remain at rest with the contact wiper 492 on a particularone of its bank of contacts 509, thereby connecting a particularselector coil or solenoid I0 in an operating circuit including powersource or battery 5| I, grounded at 5| 2, wiper 492, conductor 5|3,control relay contacts 5I4, conductor 5I5, and first control relaycontacts 5| 6 to ground 5 I 1, for energization of the particular coilor solenoid selected so soon as the first and second control relaysbecome energized following completion of the selecting operation.

When the incoming carrier or selecting signal energy arrives, thestepping switch at once starts to step, which results `in repeatedclosing and opening of relay shorting switch contacts 520 on thestepping switch, so that plate supply voltage from `conductor 430A isapplied directly to the plate 436 of the relay control tube at junction52| via conductor 522, thereby preventing operation of relays 439 and44|, both 0f the latter being shunted by condensers 522 and 523,respectively, such that they do not immediately pull up or drop out.

When the selecting pulses are matched, the stepping switch remains atrest and shortin;t contacts 529 remain open, so that the two controlrelay windings 439 and 44| have time to become energized by building upof the necessary charge in their respective shunting ctndencers; butcondenser capacity 522 is different from that of 523, and the rst relay439 pulls up ahead of the second relay, so that contacts 5| 6 closebefore second relay contacts 5|4 open, whereby the necessary operatingground for selecting wiper 492 is completed momentarily, and thephonograph or other controlled instrumentality is selectively actuatedas a result of energization of a particular one of the coils orsolenoids 5 0.

So long as the incoming signals continue to be received, said pair ofcontrol relays 439 and 44| will continue to be energized by flow ofplate current in tube 435 after the signals are matched and theselection ls made, in which case the stepping switch is at rest and itssnorting contacts 520 are open; and so long as the first control relay439 is thus energized, its normal contacts 5| 6X will remain open, thusinterrupting the cathode return circuit to ground for the last stage ofthe incoming signal shaping means, i. e. cathode 433A, conductor 524 toground 5H; thus, once the selection is made, incoming signals are lockedout and no incoming pulses are delivered to juncture 452.

However, as soon as the incoming signals cease, relay control tube 435will no longer be impulsed, and the pair of control relays 439 and 44|will drop out, breaking the lockout and normalizing the system forreception of the next selecting signals.

In the event that the carrier of the selector control unit shown in Fig.3-A is to be frequency modulated as a function of phased-modulationselecting signals as hereinbefore suggested, the demodulating means,shown as detector 228, 229, etc. in Fig. 3B, and that indicated at 4|6in Fig. 4-A, are replaced by any of the usual discriminators employed inthe art for demodulating frequency modulated carriers, suchdiscriminators boing in addition to the phase-discrimination meanshereinbefcre described.

Phase-shift metallic circuit system In Fig. 5 there is shown a modifiedembodiment of the phase -shift selecting signal system in which thesignals from the remote control stations are applied directly to ametallic circuit leading to the selector or receiver unit, instead ofemploying a carrier for space propagation or power-line transmission,with the selecting signals superimposed thereon.

In said gure, a reference standard source of alternating voltage, suchas commercial power line 500, provides across the terminals oftransformer secondary an A. C. signal voltage, which is phasally shiftedby means such as capacity 502 in series-shunt with variable resistormeans 583 across said secondary. A center-tap connection 504 from thesecondary is connected to one of a pair of line conductors 505 and 506,the latter of which connects to the juncture between said capacity andresistor. Conductors 505 and 505 may be an ordinary 2-wire pair or cableleading to the phonograph or other selecting mechamsm.

Connected to t-he terminal ends of said line pair or cable conductors,is the primary 508 of a coupling transformer, the two main secondaryterminals of which are connected to discriminator plates 5|0 and 5||,the cathodes 5|0A and 5| IA of which connect via leads 5|0B and 5| IB,through filter resistors 5|2 and 5|3 to control grids 5|4 and 5|5 of apair of gas tetrodes 5|6 and 5|`I, the same being a shield grid form ofThyratron employed as selector relay means.

A local matching signal is produced from the commercial power-linereference standard, indicated at 500A, by connection thereto oftransformer' primary 520 having secondary 52| shunt- 19 ed by phase-liftmeans such as capacity 522 in series with variable resistor 523,affording a phasal modifier or phase-shift network identical to` means502, 503 at the selecting station, the

junction between capacity 522 and resistance means 523 being connectedvia lead 524 to a center tap on the line coupling or input transformersecondary, while center tap 525 of the signal source secondary 52|connects via lead 525 to the center tap between a pair of loadrcsistors`521and 528 across the discriminator cathodes, thus completing the localsignal voltage circuit Y to the matching means or discriminator.

When the locally generated signals match-the.,

incoming selecting signals in phasal relation-,the discriminator outputis a low-amplitude `ripple of approximately sinusoidal form, whichisflatv tened out as desired by filter means including j resistors 5|2and 5|3 and capacitors 5|2A and ff- 2c Grids 5|4 and 5|5 are normallyblasedvto.; quench or cut-off voltage by battery or sourcev f 530connecting to center tap of a pair of resistors:v 53| and 532 acrosssaid grids. The two relay l.

the incoming and locally generated signals a lo cal control voltage willbe applied to one or the other of the relay tube control grids 5|4 or5|5, thus energising the step switch solenoid 535 and changing in aprogressive sense the values of resistor 523; and with each steppingoperation as aforesaid, interruptor switch 538 opens and quenches therelay tubes 5|5, 5H.

As a further consequence of stepping of the selector switch, a normallyopen grounding switch 540 is momentarily closed, thereby grounding theincoming line signals between grounds 54| and 542, so that line signals,rectied by rectifying means 543, are not applied to the control grid 544of control relay tube 545, in consequence of which grid timing capacity545 does not have suflicient time to charge up and positively chargesaid grid against the negative bias voltage of battery 541.

When the local signals phasally match the incoming signals, there is aneffective null across 4the discriminator output, so that the gas relaytubes do not re, and the stepping switch remains at rest, in consequenceof which timing capacity 546 charges up and throws grid 544 positive,causing current flow in the circuit of control tube plate 548, whichconnects through control relay windings 549 and 550 to the positiveplate supply, source, causing relay contact 549A to pull up vvvand applyground 55| via conductor 552, now normal relay contacts 553 and 554,conductor 555, to selector switch wiper 536, so that the latter willclose an operating circuit from said ground through one of the selectingcoils 556, battery or power source 551, to ground 558.

Relay winding 543 is shuntcd by timing capacity 549A, and winding 550 bycapacity 550A, such that the latter winding is slower to saturate thanthe former, whereby ground 55| can be applied before contacts 553 and554 on the second relay open.

As soon as both relays are pulled up, ground 55| for the relay tubes,through interrupter switch 538, is broken at relay contacts 549A'560,effecting a lockout against any selecting operation by incoming signalsuntil the system is normalized, as by release of the two control relays549, 550 and discharge of timing condensers 546, following cessation ofthe incoming selecting signals. l

Having thus described my invention, what I particularly point oiit anddistinctly claim as my invention, discovery, and origination is:

l. Remote control apparatus comprising a carrier transmitter and remotereceiver, identical phase modulation reference standards for said`-transmitter and said receiver, selecting signal ',modulating meansutilizing said standard for selectively modulating said carrier with anyof va plurality of phasal selecting impulses, matching' signal phasemodulation means utilizing said standard at said receiver forreproducing one at'at'time in a predetermined order the range ofselecting signal impulses aforesaid and electrically comparing the samewith received modulations, and selecting means operating responsive tosubstantial identity of compared received and matching impulses.

2. Power-line selecting means for automatic phonographs and comprisingcircuit means for transmitting over a power line different selectingimpulses which are a function of phase-angle characteristics derivedfrom an alternating voltage on said line, and remote circuit meansreceiving said impulses and comparing them electrically one at a timewith a succession of locally produced impulses which are likewisecorresponding functions of said phase-angle characteristics, andphonograph selector mechanism actuated responsive to an electricalcondition resulting from comparison of a received selecting impulse andthe identical locally produced impulse.

3. The method of controlling selective apparatus which comprisestransmission of different selecting impulses each characterized as afunction of phase angle relations derived from an alternating voltagestandard, generating one at i* a time a plurality of duplicationimpulses each likewise characterized as a function of phase anglerelations derived from said standard, electrically comparing thetransmitted impulses with duplication impulses, and actuating saidselective apparatus by the electrical condition resulting when the saidcompared transmitted and duplication impulses are substantially matchedin phasal characteristic.

4. Remote control apparatus comprising means for generating selectingsignal impulses different from each other as functions o'f phase anglerelations derived from an alternating voltage standard, means forreceiving said impulses and including apparatus for generating a multi-Aplicity of local impulses each likewise characterized as a function ofphase angle relations derived from said standard and each of whichduplicates one of said selecting impulses, means for electricallycomparing said local impulses with received selecting impulses toproduce an electrical control factor having a first characteristic whenthe received and local impulses are different, and having a secondcharacteristic when said latter impulses are substantially idenr tical,means operating under control of said control factor to vary in fixedsteps the local impulses as to phase angle characteristic so long assaid control factor has the rst characteristic until such time as thereceived and local impulses are identical as aforesaid, and meansactuating a selector device responsive to said control factor when thelatter has the second characteristic.

5. Phonograph remote control apparatus including a selecting stationhaving a thermionic oscillator coupled to an A. C. power line, meansoperated manually for selectively modulating the oscillator withphase-shifted selecting signals each corresponding to a particularphonographic selection, and derived from said A. C. line, and selectorstation apparatus including an automatic phonograph and a selectingswitch therefor, together with means for generating local phase-shiftedsignals, phasing means coacting with said selecting switch to phasallymodify the local signals to degrees of phase-shift each corresponding toone of said selecting signals and to a particular phonographic selectionselectable by said selecting switch, selector relay means for operatingsaid phasing means and saidselecting switch-'in step-by-step operation,an operating circuit for said selector relay means and into which is fedboth selecting signals 4and local signals, said selector relay meansbeing operated to effect a phonographic selection through said selectingswitch responsive to a condition dependent upon a degree of phasaldifference between said selecting and local signals, said localgenerating means and phasing means deriving phasal components from saidA. C. line, together with means for deriving selecting signals from saidline, for feeding into said operating circuit.

6. Control -apparatus as set forth in claim 5 and further characterizedby the provision therein of a timing circuit ,cooperable with said relaymeans and operating circuit to restore said apparatus to a normalnon-phonographic selecting condition after lapse of a certain timefollowing each phonographic selection effected as aforesaid.

7. Apparatus as set forth in claim 6 and further characterized by theprovision of circuit means for shaping both the selecting signals andlocal signals to corresponding wave form for electrical comparison andmatching in said operating circuit.

8. Apparatus as set forth in claim 7 and further characterized by theprovision therein of poling means for both selecting and local signalsto provide polarities therefor suitable for comparison and matchingpurposes* as aforesaid, without regard to line polarities respectingsaid A. C. line.

9. Apparatus as set forth in claim 5 and further characterized by theprovision of circuit means for shaping both the selecting signals andlocal signals to corresponding wave form for electrical comparison andmatching in said operating circuit.

10. Apparatus as defined in claim 9 and further characterized by theprovision of poling means for both selecting and local signals toprovide polarities therefor suitable-for comparison and matchingpurposes as aforesaid, without regard to line polarities respecting saidA. C. line.

11. In a remote control system, a transmitter and a receiver; means atthe transmitter for generating selecting signals different from eachother as functions of phase angle relation derived from an alternatingvoltage standard;

means for transmitting said signals to the receiver; means at saidreceiver for demodulating.

depolarizing and shaping the transmitted selecting signals and applyingsame to the input of thermionic relay means; means at the receiver forderiving from said alternating voltage standard local depolarizedsignals of shape and frequency corresponding to the selecting signals; aphase shifter effective to selectively modify the phase of said localsignal in sequential steps throughout the range of phase variation ofsaid transmitted signal; said local signals being applied to the inputof said relay means for direct comparison with said selecting signals;and circuit connections and means controlled by said thermionic relaymeans for actuating said phase shifter repeatedly in steps as aforesaidresponsive to resultant control voltages from dissimilar signals butarresting operation of said phase shifter responsive to control voltagesresultant from identical incoming and local signals.

12. In a remote control system, a transmitting station and a receivingstation, each associated with a reference source of periodic voltage;means at the transmitting station for generating a series of r. f.signal pulses which are phasallyshifted selectively relative to saidreference source; means for transmitting said signal pulses to saidreceiving station; means at the receiving station for generating aseries of trigger pulses responsive to said signal pulses, said triggerpulses being phase-shifted relative to said reference source an amountcorresponding to the phase-shift of said signal pulses; means at thcreceiving station for generating a series of comparingr pulses; meansfor shifting said comparing pulses by fixed steps into phase with saidtrigger pulses; means for comparing the phase of said trigger andcomparing pulses; and selector means actuated in response to anelectrical condition resulting from phase-shift matching of trigger andcomparing pulses in said comparing means.

13. Apparatus of the class described comprising, in combination with analternating current power line, selecting and selector means, saidselecting means including a source of signal energy coupled to saidline, a selectively variable phase-shift network cooperable with saidsignal source and operating to effect impression upon said line ofdifferent selecting signal pulses each characterized as a function ofphase angle relations derived from said power line, said selector meanscomprising input circuit means for detecting phased-modulation signalson said power line, electronic signal-squaring means, a local source ofsignal pulses also derived from said power line, circuit means forselectively varying the phasal aspect of said local signal pulses stepby step by predetermined amounts, a selecting switch having selectingpositions each corresponding to one of said varying phasal aspects andsteps and electromagnetic means for actuating said varying means andsaid selecting switch in step, electronic squaring means for said localpulses` a selecting circuit controlling operation of saidelectromagnetic means and operably energized by action therein of bothsquared selecting and local signal energy and dependent upon the degreeof phasal identity between said selecting and local signals for varyingthe phasal aspen' of the local signals and setting up a selection`operating circuit through said selecting switch at a said position ofthe latter which corresponds to a particular degree of phasal identitybetween

